Steam turbine governor valve actuating mechanism

ABSTRACT

The connecting links of the pinned pivotal joints in the turbine governor valve operating mechanism are maintained under tension by a stack of Belleville spring washers mounted in one motion transmitting member. The spring washers urge a ball against the other motion transmitting member establishing a preloaded joint between the valves and the valve actuating member. This arrangement eliminates play in the pinned joint resulting in a more stable governing system.

United States Patent 1 1 Straslicka 1 Oct. 30, 1973 STEAM TURBINEGOVERNOR VALVE ACTUATING MECHANISM Primary ExaminerMartin P. SchwadronAssistant ExaminerD. Matthews [75] Inventor. William A. Strashcka,Norvelt, Pa. AHOmey J Raymond Cum [73] Assignee: Carrier Corporation,Syracuse, N.Y. [22] Filed: July 24, 1972 [57] ABSTRACT [21] Appl, No;274,159 The connecting links of the pinned pivotal joints in the turbinegovernor valve operating mechanism are maintained under tension by astack of Belleville 2513;123:352; Spring washers mounted in one motiontransmitting Field 231 233 member. The spring washers urge a ballagainst the other motion transmitting member establishing a preloadedjoint between the valves and the valve actuating member: Thisarrangement eliminates play in the [56] References cued pinned jointresulting in a more stable governing sys- UNITED STATES PATENTS tam.

1,973,744 9/1934 Brown 251/231 3,103,131 9/1963 Banek 74/582 x 5 Claims,3 Drawing Flgum Patented- Oct. 30, 1973 3,768,776

2 Sheets-Sheet 1 STEAM TURBINE GOVERNOR VALVE AGTUATING MECHANISMBACKGROUND OF THE INVENTION In larger steam turbines, a plurality ofpoppet type valves are arranged in the valve chest to control the flowof steam to the turbine. The valves are movable in an axial directioninto and out of engagement with the valve seats. Conventionally, thevalves are connected to an operating arm movable in an arcuate pathabout a fixed axis. The actuating arm is operated by a servo motorcontrolled by the turbine governor.

The valves, and accordingly the mechanism connected thereto, aresubjected to vibration of high frequency and of substantial magnitude.

The governor valve unbalanced forces are unpredictable from the momentthe valve leaves its seat until reaching full open position. Thereversal of these forces must be contained by the valve gear linkageoperatively connecting the valves to the actuating arm. Universally,that linkage includes pinned joints. The components of these joints areproduced with manufacturing tolerances with the result there is aclearance in every pinned joint and the reaction of the governor valveforces and these clearances, regardless of how slight they may be,results in an unstable governing system. Also, with vibration of suchmagnitude, any play in such joints results in wear causing an increasein the clearances between the components making up the joint.

This invention has as an object a steam turbine governor valve actuatingmechanism embodying preloaded pivotal joints eliminating theobjectionable condition above referred to.

SUMMARY OF THE INVENTION One component of the pivotal joints, such asthe rod ends connected to the valve operating rods, is formed with acavity in which there is mounted a stack of Belleville spring washers. Ahardened ball is positioned on the stack of washers and is yieldinglyurged against the other member making up the joint, as the actuatingarm. The motion transmitting members of the joint are pivotallyconnected by links attached by pins to the members. The spring washersand ball arrangment serves to place the links under tension by apressure exceeding the unbalanced reaction forces of the governor valve,eliminating play in the pinned connections.

BRlEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view ofa steam turbine valve chest and contiguous portion of the valveoperating structure.

FIG. 2 is an enlarged view taken on line 2-2 FIG. 1.

FIG. 3 is a view taken on line 33 FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT lifting bar 16, and accordinglythe valves 15, are moved in a direction axial of the valve seats 14 byactuating members, as lifting rods 17, which are slidably mounted inguide members 18 fixed in the top wall of the valve chest.

The upper ends of the lifting rods 17 have threaded connection with rodends 20 and locked in adjusted position by lock nuts 21.

The rod ends 20 are pivotally connected to an operating arm 25 by links27 overlying opposite sides of the rod ends 20 and the actuating arm 25.The rod ends 20 and the arm 25 are formed with transversely extendingapertures to receive pivot pins 30. For further illustration of thevalve operating structure, reference may be made to US. Pat. No.3,625,541 issued Dec. 7, I971.

The end surface of each of the rod ends 20 confronting the arm 25 isformed with a cavity 31, in which there is mounted a plurality ofBelleville spring washers 33 arranged in a stack formation. Theoutermost washer 34 is positioned with the convex side thereofconfronting the actuating arm member 25. A contact member, such as ahardened ball 35, is positioned on the stack of spring washers whichfunction to yieldingly urge the ball against the confronting surface 37of the arm 25 for rolling contact therewith.

The arm 25 is mounted on the shaft 40 for oscillation about the axisthereof. The shaft 40 is journaled in a supporting structure 41 attachedto the turbine casing. The confronting surface 37 of arm 25 is formedwith a recess 43 circular in cross section, see FIG. 2. The recess 43 iselongated in a direction lengthwise of the arm 25, see FIG. 3; that is,in a direction radial from the axis of the shaft 40. The recess 43 isformed on a radius comparable to the radius of the ball 35 and, incombination with the outermost washer 34, serves to maintain the ball inoperative engagement with the arm 25.

The ball 35 provides the necessary rolling motion between the beam arm25 and the rod end 20 during operation of the mechanism in moving thevalves 15 toward and from the seats 14.

On assembly, a shim 45 is positioned in the bottom of the recess 31. Theshim 45 is of a thickness to cause the washers 33, 34 to exert a forceagainst the arm 25 greater than the governor valve reaction force.Accordingly, the side links 27 are maintained under tension, and theends of the pins 30 are tightly engaged by the links and theintermediate portions of the pins 30 are tightly engaged against theupper side of the aperture in the rod end 20, and against the lower sideof the aperture in the arm 25. This arrangement eliminates play in thejoint structure and results in an improvement in the overall turbinegoverning system. A rod 50 is connected to the free end of the arm 25,and is reciprocated by a servo motor controlled by the turbine governor.

I claim:

I. A steam turbine governor valve actuating mechanism comprising a valveactuating member connected to the valve and movable in a linear path, anoperating member movable in an arcuate path, said members havingsurfaces disposed in spaced confronting relation, connecting linkspivotally attached to said members, one of said members being formed inthe confronting surface thereof with a cavity, a plurality of Bellevillespring washers in said cavity, a contact member positioned intermediatesaid stack and the confronting surface of said other member and havingroll- 4. A steam turbine governor valve actuating mechanism as set forthin claim 1, wherein the confronting surface of said other member isformed with a recess dimensioned to receive said contact member forrolling engagement therewith.

5. A steam turbine governor valve actuating mechanism as set forth inclaim 1, wherein the outermost washer in said stack is disposed with theconvex side thereof facing said other member and said contact memberconsists of a ball positioned in said outermost member.

1. A steam turbine governor valve actuating mechanism comprising a valveactuating member connected to the valve and movable in a linear path, anoperating member movable in an arcuate path, said members havingsurfaces disposed in spaced confronting relation, connecting linkspivotally attached to said members, one of said members being formed inthe confronting surface thereof with a cavity, a plurality of Bellevillespring washers in said cavity, a contact member positioned intermediatesaid stack and the confronting surface of said other member and havingrolling engagement therewith, said spring washers yieldingly urging saidcontact member against said surface of said other member at a pressureexceeding the governor valve reaction forces to maintain said connectinglinks under tension.
 2. A steam turbine governor valve actuatingmechanism as set forth in claim 1, wherein said contact member is a ballof hardened material.
 3. A steam turbine governor valve actuatingmechanism as set forth in claim 1, wherein said cavity is formed in theconfronting surface of said valve actuating member.
 4. A steam turbinegovernor valve actuating mechanism as set forth in claim 1, wherein theconfronTing surface of said other member is formed with a recessdimensioned to receive said contact member for rolling engagementtherewith.
 5. A steam turbine governor valve actuating mechanism as setforth in claim 1, wherein the outermost washer in said stack is disposedwith the convex side thereof facing said other member and said contactmember consists of a ball positioned in said outermost member.